feat: add function property attribute

src/AnthropicClient/Models/FunctionPropertyAttribute.cs

@@ -0,0 +1,49 @@
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Attribute to describe a property of a type that is used as a function parameter.
+/// </summary>
+[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field)]
+public class FunctionPropertyAttribute : Attribute
+{
+  /// <summary>
+  /// Description of the property.
+  /// </summary>
+  public string Description { get; } = string.Empty;
+
+  /// <summary>
+  /// Whether the property is required.
+  /// </summary>
+  public bool Required { get; } = false;
+
+  /// <summary>
+  /// Default value of the property.
+  /// </summary>
+  public object? DefaultValue { get; } = null;
+
+  /// <summary>
+  /// Possible values of the property.
+  /// </summary>
+  public object[]? PossibleValues { get; } = null;
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="FunctionPropertyAttribute"/> class.
+  /// </summary>
+  /// <param name="description">Description of the property.</param>
+  /// <param name="required">Whether the property is required.</param>
+  /// <param name="defaultValue">Default value of the property.</param>
+  /// <param name="possibleValues">Possible values of the property.</param>
+  /// <returns>A new instance of the <see cref="FunctionPropertyAttribute"/> class.</returns>
+  public FunctionPropertyAttribute(
+    string description,
+    bool required = false,
+    object? defaultValue = null,
+    object[]? possibleValues = null
+  )
+  {
+    Description = description;
+    Required = required;
+    DefaultValue = defaultValue;
+    PossibleValues = possibleValues;
+  }
+}